Hydrocarbon conversion with a selectively sulfided acidic multimetallic catalytic composite

Abstract

Hydrocarbons are converted by contacting them at hydrocarbon conversion conditions with a selectively sulfided acidic multimetallic catalytic composite comprising a combination of catalytically effective amounts of a platinum group component, a sulfided rhenium component and a halogen component with a porous carrier material formed from Ziegler alumina. The platinum group component, sulfided rhenium component and halogen component are present in the multimetallic catalytic composite in an amount, calculated on an elemental basis, corresponding to about 0.01 to about 2 wt. % platinum group metal, about 0.01 to about 2 wt. % rhenium, about 0.1 to about 3.5 wt. % halogen and sulfur in an amount at least sufficient to provide an atomic ratio of sulfur to rhenium of at least about 0.5:1. These metallic components are, moreover, relatively uniformly dispersed throughout the Ziegler alumina carrier material in carefully controlled oxidation state such that substantially all of the platinum group metal is present therein in the elemental metallic state and a substantial portion of the rhenium present therein is maintained in a sulfided state. A key feature of the hydrocarbon conversion process using the subject catalyst involves the continuous maintenance of the sulfided state of the rhenium component for the duration of the hydrocarbon conversion process. A specific example of the type of hydrocarbon conversion process disclosed herein is a process for the catalytic reforming of a low octane gasoline fraction wherein the gasoline fraction and a hydrogen stream are contacted with the instant selectively sulfided acidic multimetallic catalyst at reforming conditions.

We claim as our invention: 
     
       1. In a process for converting a hydrocarbon which comprises contacting the hydrocarbon at hydrocarbon conversion conditions with a selectively sulfided acidic catalytic composite comprising a porous carrier material containing, on an elemental basis, about 0.01 to about 2 wt. % platinum group metal, about 0.01 to about 2 wt. % rhenium, and about 0.1 to about 3.5 wt. % halogen; wherein the platinum group metal and rhenium are uniformly dispersed throughout the porous carrier material; wherein substantially all of the platinum group metal is present in the elemental metallic state; wherein the composite contains sulfur in an amount at least sufficient to provide an atomic ratio of sulfur to rhenium of about 0.5:1 so that a substantial portion of the rhenium is maintained in a sulfided state; and wherein the sulfided state of the rhenium is continuously maintained for the duration of the hydrocarbon conversion process, the improvement which comprises the use of a Ziegler alumina as said porous carrier in combination with said platinum group metal component, said sulfided rhenium component and said halogen component. 
     
     
       2. A hydrocarbon conversion process as defined in claim 1 wherein the platinum group metal is platinum. 
     
     
       3. A hydrocarbon conversion process as defined in claim 1 wherein the platinum group metal is iridium. 
     
     
       4. A hydrocarbon conversion process as defined in claim 1 wherein the platinum group metal is rhodium. 
     
     
       5. A hydrocarbon conversion process as defined in claim 1 wherein the halogen is combined chloride. 
     
     
       6. A hydrocarbon conversion process as defined in claim 1 wherein the catalytic composite is selectively sulfided after substantially all of the platinum group metal and rhenium contained therein are reduced to the elemental metallic state by contacting the reduced catalytic composite with a sulfiding reagent in an amount and under conditions selected to convert a substantial portion of the rhenium to the sulfided state while maintaining substantially all of the platinum group metal in the elemental state. 
     
     
       7. The hydrocarbon conversion process as defined in claim 1 wherein the selectively sulfided acidic catalytic composite is prepared by the steps of: (a) forming a composite comprising a combination of the specified amounts of platinum group metal, rhenium and halogen with the Ziegler alumina carrier material in which substantially all of the platinum group metal and rhenium are present in the corresponding oxide form;   (b) subjecting the resulting oxidized catalytic composite to reduction conditions effective to reduce substantially all of the platinum group and rhenium components to the corresponding elemental metallic state;   (c) sulfiding the resulting reduced composite by contacting same with a sulfiding reagent in an amount and under conditions at least sufficient to convert a substantial portion of the rhenium component and of the platinum group component to the corresponding sulfided state; and thereafter,   (d) stripping substantially all of the sulfide from the platinum group component resulting from step (c), while maintaining a substantial portion of the rhenium component in a sulfided state.   
     
     
       8. A hydrocarbon conversion process as defined in claim 1 wherein the composite contains about 0.05 to about 1 wt. % platinum group metal, about 0.05 to about 1 wt. % rhenium, and about 0.5 to about 1.5 wt. % halogen and wherein sulfur is present therein in an amount sufficient to result in an atomic ratio of sulfur to rhenium of about 0.5:1 to about 1.5:1. 
     
     
       9. A hydrocarbon conversion process as defined in claim 1 wherein the contacting of the hydrocarbon with the selectively sulfided acidic catalytic composite is performed in the presence of hydrogen. 
     
     
       10. A hydrocarbon conversion process as defined in claim 1 wherein the type of hydrocarbon conversion is catalytic reforming of a gasoline fraction to produce a high octane reformate, wherein the hydrocarbon is contained in the gasoline fraction, wherein the contacting is performed in the presence of hydrogen and wherein the hydrocarbon conversion conditions are reforming conditions. 
     
     
       11. A process as defined in claim 10 wherein the reforming conditions include a temperature of about 800° to about 1100° F., a pressure of about 0 to about 1000 psig, a liquid hourly space velocity of about 0.1 to about 10 hr. -1 , and a mole ratio of hydrogen to hydrocarbon of about 1:1 to about 20:1. 
     
     
       12. A process as defined in claim 10 wherein the contacting is performed in a substantially water-free environment. 
     
     
       13. A process as defined in claim 1 wherein the selectively sulfided state of the catalytic composite is maintained by continuously or periodically adding a sulfiding reagent to the process in an amount corresponding to about 0.1 to about 20 wt. ppm. of the hydrocarbon charge.